It is well known that a valve timing adjusting device is arranged in a power transmission passage that transmits a power from a driving shaft of an internal combustion engine to a driven shaft of the internal combustion engine, and the valve timing adjusting device adjusts a valve timing of an intake valve or an exhaust valve which is driven to open and to close by the driven shaft. When the valve timing adjusting device is hydraulic, the valve timing adjusting device includes a housing that rotates in association with one of the driving shaft and the driven shaft and a vane rotor that is fixed to an end portion of the other one of the driving shaft and the driven shaft. Further, the vane rotor rotates relative to the housing in an advance direction or a retard direction by supplying an operation oil to one of a first oil pressure chamber and a second oil pressure chamber which are included in the housing. A supply of the operation oil is executed by an oil channel switching valve.
According to U.S. Pat. No. 8,910,602B2, in the valve timing adjusting device, the oil channel switching valve is a valve that is arranged at a center portion of the vane rotor and includes a spool. The oil channel switching valve includes a sleeve that includes various ports, and the spool that moves in the spool in an axial direction of the spool.
The sleeve is a tubular shape and extends in the axial direction. The sleeve includes a supply port, a first drain port, a first control port, a second control port, and a second drain port, in this order from a cam shaft. The supply port communicates with an oil supply channel of the cam shaft. The first drain port communicates with a first drain space that is placed at a position out of the cam shaft, through a drain oil channel that penetrating the cam shaft in a radial direction. The first control port communicates with the first oil pressure chamber. The second control port communicates with the second oil pressure chamber. The second drain port communicates with a second drain space opposite to the cam shaft relative to the vane rotor.
The spool includes an oil connection channel that is arranged at an axial center portion of the spool and controls the supply port to be connected with the first control port or the second control port depending on an axial-direction position of the spool.
When the operation oil is supplied to the first oil pressure chamber, the oil channel switching valve controls the supply port to be connected with the first control port and controls the second control port to be connected with the second drain port. In this case, the operation oil in the second oil pressure chamber flows into the second drain port through the second control port, and then is discharged to the second drain space. When the operation oil is supplied to the second oil pressure chamber, the oil channel switching valve controls the supply port to be connected with the second control port and controls the first control port to be connected with the first drain port. In this case, the operation oil in the first oil pressure chamber flows into the drain oil channel through the first control port and the first drain port, and then is discharged to the first drain space.